It's finished size is 83 feet high by 161 feet wide.
The water in the fountain "is regarded to furnish some of the purest drinking-water in Rome, reputed for its restorative qualities. Many people to this day can be seen filling containers for drinking and cooking in its splendid fountains." It also at one time fed the hot baths of Agrippa for over 400 years.
My favorite fun fact about the fountain: "An estimated 3,000 Euros are thrown into the fountain each day. The money has been used to subsidize a supermarket for Rome's needy; however, there are regular attempts to steal coins from the fountain."